Simon Coveney received a campaign boost last night when prominent MEP Mairead McGuinness weighed in behind him as Fine Gael members prepared to vote for their next party leader.

Ms McGuinness had been widely suspected to support Mr Coveney but had insisted she would not declare for either candidate until the campaign hustings took place.

However, in a statement, she said she was backing the Housing Minister because he had shown "grit and determination" by staying in the leadership race when others thought he should step aside.

"In sticking to the race, he has shown a particular passion for leadership - and has also demonstrated an important leadership attribute in not giving up when the going gets tough," she said.

"He has taken his message to the country - to the membership - and the party is the better for that open and frank debate about the direction that our party should take," she added.

Meanwhile, Mr Coveney launched an extraordinary attack on Leo Varadkar's "flashy" leadership campaign and raised concerns over how much money has been pumped into his rival's election war chest.

Speaking to the Sunday Independent on the eve of the final leadership debate, Mr Coveney rounded on his opponent and insisted he did not need "slick PR launches" or "fancy T-shirts" to win over party members.

The Housing Minister's intervention came after it emerged that Mr Varadkar was holding secret fundraising events in members-only clubs in Dublin city centre.

"From my own point of view, every penny we've raised in this campaign has been raised in the normal way through the normal rules," Mr Coveney told the Sunday Independent.

"We fundraised for a campaign that is more about message than it is about spin and more about substance than slick PR launches," he added.

Mr Varadkar's spokesman issued a statement insisting all campaign donations received were in line with political fundraising rules.

"Campaigns such as this cost money and donations are a normal part of the political process," he said. "A reception was held during the week for people who had contributed. The party will be supplied at the end of the campaign with details of expenditure in compliance with all State and party requirements."

Before the leadership contest officially began, Mr Varadkar's supporters sought to have a spending cap introduced for candidates - but the proposal was shot down by Fine Gael headquarters.

Mr Coveney said his rival's campaigners accused him of pumping funds into an election war chest as part of an attempt to "paint a picture that wasn't true".

However, since the campaign has begun, it has been clear to onlookers that Mr Varadkar's camp of supperters has put more resources into their man's bid to become the next Taoiseach.

"The very picture they tried to paint of me is exactly what they are doing themselves and I don't think people buy it," Mr Coveney said.

"I think as the campaign has rumbled on, people can see I am about my message, not about slick events or fancy T-shirts.

"It has been a blunt, strong and ambitious message for the country. I think that's what is changing the momentum in this race, not the big spending campaign that we are clearly up against."

Mr Varadkar has held a number of fundraising events recently. These have included a fundraiser hosted by Thomas Lynch, who is chair of Dublin East Hospital Group and whose remit includes St Vincent's University Hospital and the National Maternity Hospital.

'Each week on the Floating Voter, INM's political team discuss the main issues affecting Irish politics, bursting the bubble that surrounds Leinster House.'

Mr Varadkar has also put policies in his election manifesto that Mr Coveney wrote, the Housing Minister claimed.

He said: "Look at Leo's manifesto on the marine and he talks about Ireland having for the first time a full maritime strategy for the country. I wrote that - and I implemented it.

"He talks about Food Wise 2025 as the roadmap for the food industry - I wrote it and I'm implementing it."

Mr Coveney, who previously served as minister for agriculture, food and the marine, insisted he was the best candidate to address the needs of rural Ireland.

He added: "Who do they want as Taoiseach? Someone who has been down and dirty in those communities and has tried to find a way of supporting them or someone who has it in their manifesto, talking about things I've done?"

Mr Varadkar is expected to publish his rural policies at an event in Cavan tomorrow.

Mairead McGuinness's support means Mr Coveney now has the votes of 21 TDs compared to Mr Varadkar's 46.

Mr Coveney's supporters believe they can secure the support of the remaining undeclared voters, who include Taoiseach Enda Kenny, Finance Minister Michael Noonan, Agriculture Minister Michael Creed, MEP Sean Kelly and some TDs.

Fine Gael parliamentary party endorsements for leader

The Fine Gael parliamentary party makes up 65pc of the total electorate.

That makes each of the 73 members' votes worth 0.9pc of the total ballot.

Of the remaining electorate, 230 party councillors account for 10pc, while the remaining 25pc is rank and file members.

Leo Varadkar

Simon Coveney

Total: 45

Total: 19

Ministers: 17

Ministers: 5

TDs: 16

TDs: 5

Senators: 11

Senators: 8

MEPs: 1

MEPs: 1

Richard Bruton -Minister

Simon Harris - Minister

Frances Fitzgerald - Minister

Damien English - Minister

Michael Ring - Minister

Dara Murphy - Minister

Eoghan Murphy - Minister

David Stanton - Minister

Sean Kyne - Minister

Marcella Corcoran Kennedy - Minister

Joe McHugh - Minister

Kate O'Connell - TD

Helen McEntee - Minister

Maria Bailey - TD

Charlie Flanagan - Minister

Sean Barrett TD

Paul Kehoe -Minister

Hildegard Naughton - TD

Patrick O'Donovan - Minister

Peter Fitzpatrick - TD

Regina Doherty - Minister

Tim Lombard - Senator

Mary Mitchell O'Connor - Minister

Jerry Buttimer - Senator

Paschal Donohoe - Minister

Paudie Coffey - Senator

Heather Humphreys - Minister

James Reilly - Senator

Pat Breen - Minister

Colm Burke - Senator

Catherine Byrne - Minister

John O'Mahony - Senator

Andrew Doyle - Minister

Paul Coghlan - Senator

John Paul Phelan - TD

Gabrielle McFadden - Senator

Noel Rock - TD

Deirdre Clune - MEP

Tony McLoughlin - TD

Alan Farrell - TD

Michael D'Arcy - TD

Tom Neville - TD

Josepha Madigan - TD

Pat Deering - TD

Jim Daly - TD

Brendan Griffin - TD

Ciaran Cannon - TD

Colm Brophy - TD

Peter Burke - TD

Fergus O'Dowd - TD

John Deasy - TD

Joe Carey - TD

Neale Richmond - Senator

Catherine Noone - Senator

Paddy Burke - Senator

Martin Conway - Senator

Michelle Mulherin - Senator

Maura Hopkins - Senator

Ray Butler - Senator

Frank Feighan - Senator

Maria Byrne - Senator

Joe O'Reilly - Senator

Kieran O'Donnell - Senator

Brian Hayes - MEP

Undeclared

Enda Kenny - Outgoing Party Leader *

Martin Heydon - Party Chairman *

Michael Noonan - Minister

Michael Creed - Minister

Bernard Durkan - TD

Sean Kelly - MEP

Mairead McGuinness MEP

* Outgoing leader Enda Kenny and party chairman Martin Heydon will not make an endorsement